Resuscitation masks employed to co-operate with an operator's mouth and the face of a victim to be resuscitated have been in use for many years. Virtually all the masks in use today employ a one-way valve that is interposed between a mouth of an operator and a mouth of a victim who has stopped breathing and needs to be resuscitated to restore breathing.
In recent years there has been an increased awareness that a victim in need of resuscitation is possibly infected with the deadly acquired immune deficiency syndrome (AIDS) and considerable effort has been expended to prevent contamination of a rescuer or resuscitation mask operator. The virus responsible for AIDS is normally contained within a victim's body fluids. It is believed that absent blood in a victim's saliva, mucous or regurgitated matter there is little risk of cross contamination to the operator by breath exhaled by the victim.
Recently there has been a startling resurgence of tuberculosis in the world. This dreaded disease once believed to be wiped out is now experiencing a resurgence in populations of people living in urban and rural environments. In rural environments this disease is commonly carried by migrant farm workers.
Tuberculosis is an air-borne pathogen that is passed between infected individuals and healthy individuals via the exhaled breath from the lungs of a tuberculosis infected individual.
There have been many enhancements to the one-way valves employed in mouth-to-mouth resuscitation masks in order to prevent the transmission of the AIDS virus from a victim to an operator. Little, if anything, appears to have been done to specifically prevent air-borne pathogens present in a victim's exhaled breath from reaching an operator's mouth and lungs, with the exception of filters that restrict air flow.
One feature of the invention to be described herein after provides a remedy to this new concern regarding air-borne pathogens.
The level of technical sophistication in one-way valve structures for use in a resuscitation mask is shown in U.S. Pat. No. 4,811,730 ('730) issued Mar. 14, 1989 to A. J. J. Milano. The '730 patent teaches the use of a pair of one-way valves in a cardio pulmonary resuscitation (CPR) mask. One of the valves allows a rescuer's breath to pass into the nose and mouth of a victim while preventing the victim's exhaled breath from entering the rescuer's mouth. A second one-way valve member is provided to permit the rescuer's breath to pass therethrough and into an inflatable bladder while simultaneously preventing the air in the bladder from escaping. The inflatable bladder creates a resilient sealing means between a face of a victim and the resuscitation mask.
The first one-way valve member which is typical of the prior art includes a moveable valve member 42 which does not provide a hermetic seal with the walls of a chamber through which it travels. Air borne pathogens may leak past the moveable valve member and reach the rescuer's mouth and lungs. The instant invention prevent this type of cross contamination from occurring by providing a hermetic sealing between a moveable valve member of a one-way valve and the mouth and lungs of the rescuer.
In addition to public concerns regarding air-borne pathogens and one-way valves employed in, mouth-to-mouth resuscitation masks it is additionally recognized that many occupations such as, paramedics, firemen, hospital staff, lifeguards, etc., may require the personnel to administer CPR to a non-breathing victim who is removed from areas where more bulky equipment such as bag-valve-masks or demand valve resuscitators are stored. It has become a necessity to have these people carry a protective resuscitation device that can be applied to the victim immediately to start artificial ventilation while fellow workers bring bulkier equipment to the scene.
The device needs to be compact so it can be conveniently carried in a pocket by these personnel. The compactness should not compromise the efficiency of the device. Another criteria to consider is the elimination of as many steps as possible in the assembly of the device prior to resuscitation.
One of the more common type of devices in administering mouth-to-mouth ventilation is with an anesthia type mask. This type of mask seals around the victim's mouth and nose. These masks typically have a cuff or rim, the part of the mask that seals against the victim's face, that are made to hold entrapped air. This forms a flexible cushion which adjusts to seal various face sizes. This cuff is then connected to a dome that has a tubular fitting extending away from the dome for passage of air/gases into and out of the mask. A one-way valve or as it is frequently described, a nonrebreathing valve is inserted into this tube to allow the operator to blow into the mask and the victim's exhaled air exits away from the operator. This valve is necessary to help isolate the victim's breath from the operator.
To achieve the compactness needed for this type of mask it is taught by Laerdal, U.S. Pat. No. 4,062,357 ('357), that a dome part of the mask may be folded down to fit inside the walls of the cuff. The '357 patent shows a tubular stem at the apex of the dome extending upward inside a pocket that is formed when the dome is folded down into the cuff during storage. This tube is shown to be as long as the cuff is high. Adjacent to this tube is stored a small non-rebreathing valve, not shown in the patent.
The limited amount of room in this pocket, because of this tube, allows only for a valve of a small design to be stored on its side in this space. The smaller the valve the more restricted the air flow will be for both the victim's exhalation and inspiratory flow. Efficiency of air flow in a valve is so important that the ISO Draft International Standard #8382 sets maximum limits for the backpressure for both the patient's inspirator and exhalation air flow. A larger size valve in comparison to a valve of the same design but smaller will have less backpressure flow resistance. It is necessary to have the largest valve possible to meet those standards and to keep air flow backpressure to a minimum.
The smaller size valve also reduces the size of the mouthpiece on the valve. This small mouthpiece makes it more difficult for the operator to seal his lips around and at the same time blow into the valve in order to ventilate the victim's lungs.
The extending tubular stem also prevents the option of having the valve permanently attached to the mask. Any increase in height of the tube elevates the valve, should it be attached, and thus makes it more bulky.
To achieve maximum compactness when the mask is folded down while storing a larger valve that has more efficient air flow with a larger mouthpiece, the air inlet tube of the mask needs to be eliminated and the air inlet opening in the dome of the mask made larger enough to allow part of the valve housing to extend into this opening when the dome is folded down inside the walls of the cuff.
The multi-stage mouth-to-mouth resuscitation valve embodying the invention when employed in combination with a mask of a type to be described avoids the deficiencies noted with the use of prior art mask arrangements such as that shown in the Laerdal '357 patent.